leetcode shell题解

195. Tenth Line

 print just the 10th line of a file?

sed -n '10,10p' file.txt

194. Transpose File

For example, if file.txt has the following content:

name age
alice 21
ryan 30

Output the following:

name alice ryan
age 21 30

awk '{
for(i=1;i<=NF;i++) 
    {
        if(1==NR){
            s[i] = $i;
        }
        else{
            s[i] = s[i]" "$i;  
        }
    }
    } END {
        for(i=1;s[i]!="";i++)  
        print s[i];  
    }' file.txt

193. Valid Phone Numbers

 

two formats: (xxx) xxx-xxxx or xxx-xxx-xxxx. (x means a digit)

grep -P '^(\d{3}-|\(\d{3}\) )\d{3}-\d{4}$' file.txt

192. Word Frequency

For example, assume that words.txt has the following content:

the day is sunny the the
the sunny is is

Your script should output the following, sorted by descending frequency:

the 4
is 3
sunny 2
day 1

答案：

cat words.txt | awk '{for(i=1;i<=NF;i++) a[$i]++} END {for(i in a) print i,a[i];}' |sort -k 2nr